Chapter 2 Documenting Business Processes and Information Systems

Learning Objectives • To read and evaluate data flow diagrams • To read and evaluate system flowcharts • To read and evaluate entity-relationship diagrams • To prepare data flow diagrams from a narrative • To prepare system flowcharts from a narrative Copyright © 2004 South-Western. All rights reserved. 2

Data Flow Diagrams (DFD) • Context diagram Ø Top-level diagram • Physical flow diagram Ø Internal entity Ø External entity • Logical data flow diagram Ø Process and flow of data • Systems flow charts Ø Information processes and operations processes Copyright © 2004 South-Western. All rights reserved. 3

Data Flow Diagram (DFD) Symbols NOTES: a. A bubble can be either an entity on a physical data flow diagram or a process on a logical data flow diagram. b. The data store symbol may represent a view—a portion—of a larger entity-wide database. FIGURE 2. 1 Copyright © 2004 South-Western. All rights reserved. 4

A Context Diagram FIGURE 2. 2 Copyright © 2004 South-Western. All rights reserved. 5

A Physical Data Flow Diagram FIGURE 2. 3 Copyright © 2004 South-Western. All rights

A Logical Data Flow Diagram (Level 0 Diagram) FIGURE 2. 4 Copyright © 2004

Balanced Data Flow Diagrams • The next five slides depict “balanced” data flow diagrams. • Balanced DFDs exist when the external data flows are equivalent. • The first DFD is a context diagram and the next one is an “explosion” of it into a level 0 logical DFD. • The next diagram is an “explosion” of the logical level 0 DFD, and so on. Copyright © 2004 South-Western. All rights reserved. 8

A Set of Balanced DFDs FIGURE 2. 5 a Copyright © 2004 South-Western. All

A Set of Balanced DFDs (cont’d) FIGURE 2. 5 b Copyright © 2004 South-Western.

A Set of Balanced DFDs (cont’d) NOTES: 1. There is no Diagram 2. 0, as process 2. 0 is an elementary process (i. e. , it cannot be exploded further). 2. Assume that bubbles 1. 1, 1. 2, 1. 3, 1. 4, 3. 1. 1, 3. 1. 2, and 3. 2 are elementary processes. Copyright © 2004 South-Western. All rights reserved. FIGURE 2. 5 c 11

Systems Flowcharting Symbols FIGURE 2. 6 a Copyright © 2004 South-Western. All rights reserved.

Systems Flowcharting Symbols (cont’d) FIGURE 2. 6 b Copyright © 2004 South-Western. All rights

Common System Flowcharting Routines • The following slides show several common ways of showing processing using system flowcharting. • Pay particular attention to the way the columns are set up to communicate the flow of activities between processing entities. Copyright © 2004 South-Western. All rights reserved. 14

Common Systems Flowcharting Routines (c) Update sequential data store (a) Enter document into computer via keyboard, edit input, record input Copyright © 2004 South-Western. All rights reserved. FIGURE 2. 7 a 15

Common Systems Flowcharting Routines (cont’d) (d) Preparation and later manual reconciliation of control totals

Common Systems Flowcharting Routines (cont’d) (e) Key and key verify inputs FIGURE 2. 7

Common Systems Flowcharting Routines (cont’d) (f) Enter document into computer using scanner (g) Enter document into computer using scanner and manual keying FIGURE 2. 7 d Copyright © 2004 South-Western. All rights reserved. (e) Key and key verify inputs 18

Entity-Relationship (E-R) Diagram FIGURE 2. 8 Copyright © 2004 South-Western. All rights reserved. 19

Table of Entities and Activities for Causeway Cash Receipts System Entities Para Activities Customers Mailroom (clerk) 1 1 1. 2. 3. 4. 5. Mailroom (clerk) Accounts receivable (clerk) 1 2 2 6. 7. 8. Computer Computer Cashier Computer Accounts receivable (clerk) 2 2 2 4 3 3 3 4 4 4 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. Accounts receivable (clerk) 4 19. Send checks and remittance advices. Endorses checks. Writes amount paid and check number on the remittance advice. Prepares a batch total of the remittance advices. Sends the batch of remittance advices and the batch total to the accounts receivable clerk. Sends the batch of checks to the cashier. Enters the batch into the computer. Keys the batch total, the customer number, the invoice number, the amount paid, and the check number. Verifies the invoice is open and the correct amount is being paid. Updates the accounts receivable master data. Notifies the clerk of errors. Logs check number and amount paid. Prints a deposit slip. Compares the deposit slip with the batch of checks. Takes the deposit to the bank. Creates a cash receipts listing. Prints a summary of customer accounts paid. Compares the computer reports with the remittance advices and batch totals. Sends the total of cash receipts to the general ledger office. TABLE 2. 1 Copyright © 2004 South-Western. All rights reserved. 20

Causeway Context Diagram FIGURE 2. 10 Copyright © 2004 South-Western. All rights reserved. 21

Causeway Current Physical DFD FIGURE 2. 11 Copyright © 2004 South-Western. All rights reserved.

Table of Entities and Activities for Causeway Cash Receipts System (Annotated) TABLE 2. 2

Causeway Current Logical DFD (Level 0) FIGURE 2. 12 Copyright © 2004 South-Western. All

Drawing DFD Diagrams • The basic steps of the process are: Ø Create or obtain an accurate and reliable narrative. Ø From the narrative, create a complete table of entities and activities. Ø Draw a context diagram with external entity boxes by distinguishing carefully between internal and external entities. Ø Draw current physical flow diagrams by creating bubbles for internal entities, and showing flows to and from all entities and data stores. Ø Draw current logical flow diagrams by grouping activities that occur together, and naming the logical sub-processes each describes. Copyright © 2004 South-Western. All rights reserved. 25